when you use soundfiles in documents\Arma 3\sound and the server has configured MaxCustomFileSize = 0 ( or lower as your soundfiles size) then you will be kicked from the server and then need to close arma 3, rename folder or delete the sounds of documents\Arma 3\sound to be able to join the server. Instead of this, Arma 3 should check this circumstance and then not load the soundfiles and join the server instead of forcing you to rename or delete the documents\Arma 3\sound folder.